The half-life of 32Si:: a new estimate based on varved lake sediments

Cosmic ray produced Si-32 has found several applications as a tracer in aqueous geochemical processes. These applications require precise knowledge of the half-life of Si-32. The reported values show a wide range that varies from 101 +/- 18 to 330 +/- 40 years, thus leaving the question of the half-life of Si-32 Still wide open. In this study, we have determined the half-life of Si-32 to be 178 +/- 10 years by measuring the decrease of its activity with depth in an accurately dated varved sediment core from the Kassjon lake, North Sweden. This result reinforces the use of Si-32 as a geochronometer to study earth surface processes that have occurred during the last millennium. (C) 1998 Elsevier Science B.V. All rights reserved.